Parameters that control the characteristics of the database
    root file associated with the database or that control the
    characteristics that apply to the entire database. You can
    specify these parameters for either single-file or multifile
    databases except as noted in the individual parameter
    descriptions. For more information about database parameters
    and details about how they affect performance, see the Oracle
    Rdb7 Guide to Database Performance and Tuning.

    The ALTER DATABASE statement does not let you change all database
    root file parameters that you can specify in the CREATE DATABASE
    statement. You must use the EXPORT and IMPORT statements to
    change a number of storage area parameters. For more information
    on changing storage area parameters, see the IMPORT statement.